EXCIPLEX EMISSION IN BILAYER POLYMER LIGHT-EMITTING DEVICES

Photoluminescent and electroluminescent studies of bilayer heterojunct ions formed from a poly(pyridyl vinylene phenylene vinylene) (PPyVPV) derivative and poly(vinyl carbazole) (PVK) show an emission peak which cannot be ascribed to either the PPyVPV derivative or PVK layer. Thro ugh studies of absorption and photoluminescence excitation (PLE) spect ra we demonstrate that the additional feature results from an exciplex at the bilayer interface. The photoluminescence efficiency of the exc iplex is greater than 20%. The electroluminescence spectrum from the b ilayer devices is entirely due to exciplex emission, with internal eff iciencies initially achieved exceeding 0.1%. (C) 1997 American Institu te of Physics.